Reaching the million-dollar mark by retirement age is a challenge, but it's not impossible. There are approximately 233,000 people with at least $1 million in their 401(k) accounts, according to research from Fidelity Investments. But if your goal is to eventually join that exclusive club, you'll need a strategy.

Although saving a substantial amount of money for retirement is easier if you start earlier in life, you can still retire a millionaire even if you're off to a late start. If you're just beginning to save, these three steps can help you retire rich.

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1. Calculate how much you should be saving each month

Knowing you want to save $1 million by retirement age is only one half of the equation; it's just as important to know how much you should be saving every month to reach that goal.

Exactly how much you should be socking away will largely depend on your age. The older you are and the less time you have before retirement, the more you'll need to save each month. Depending on how many years you have left to save, you might need to contribute thousands of dollars per month to reach millionaire status.

To determine your monthly savings goal, use a compound interest calculator and play around with the inputs. For instance, if you have 30 years left before retirement and you're earning a 7% annual rate of return on your investments, you'd need to save around $900 per month to accumulate $1 million in savings. But if you only have 25 years until you retire, all other factors remaining the same, you'd need to save roughly $1,400 per month.

2. Make adjustments to your budget

Once you have a monthly savings goal in mind, the next step is to figure out where you'll find that money. Chances are you'll have to make some financial sacrifices to save as much as you need, and you might have to make some serious budget cuts if your goal is to contribute several hundred or even thousands of dollars per month to your retirement fund.

First, make a list of all your expenses and immediately slash the unnecessary ones -- such as that gym membership you don't use or subscription services you forgot to cancel. Next, try to cut back on some of the nice-to-have costs, like eating out or online shopping.

Finally, see if there are ways you can reduce your necessary expenses. Some costs, like your mortgage or loan payments, may not have much wiggle room unless you're willing to make some major life changes, like downsizing to a smaller home or selling your car. But if you get creative, you may be able to reduce your grocery bill, utilities bills, cable bill, and other monthly expenses.

3. Make sure you're investing aggressively enough

While it may be tempting to invest more conservatively to lower your risk of losing money on your investments, taking a "safer" approach can sometimes do more harm than good. If you're investing primarily in bonds and other less risky investments, you'll also see lower rates of return than if you were investing more aggressively in stocks -- making it much more difficult to reach your savings goal.

Of course, you still want to limit your risk as much as you can, even when you're investing aggressively. Throwing all your money behind a single up-and-coming stock could be a disaster waiting to happen, so it's important to diversify your portfolio and invest wisely.

To reduce your risk while still maximizing your returns, you may choose to invest in index and mutual funds. These types of investments provide instant diversification while still earning higher average rates of return than more conservative investments, which can help your savings grow faster.

Retiring a millionaire can be difficult

Reaching retirement age with at least $1 million in the bank is tough, especially if you're starting from scratch with no savings. While taking these steps can help you save a significant amount of money, achieving millionaire status may not be feasible for everyone. However, saving even a little is better than saving nothing, so try not to get too hung up on retiring a millionaire and focus more on saving as much as you can afford.